Preparation of mixtures of rubbery butadiene styrene copolymer with resinous polymerof vinyl or vinylidene chloride



PREPARATION OF OF RUBBERY BUTADIENE STYRENE COPOLYMER WITH RESIN OUSPOLYMER OF'VINYL' R VINYLI-s DENE CHLORIDE r 7 Stuart A.- Harrison,fStow, Ohio, and Walter E. Brown, Cambridge, Mass., assignors, to The'B.F Goodrich Cmnlmly, New York, Y-, a rporation orlvNw York No Drawing.Original application May 23, 1946, Serial v No; 671,897,noW-Pa'tent'No.2,614,089,;dated0ctober 14, 1952. Dividedand thisapplication January 5, 1952,

SerialNo.272,503 s I ,4 Claima t-(Cl- 260-455) 1 This invention relatesto synthetic polymerici'riaterialsr and to-a-method of p'rep'aringthe-sainmfaiid-is especia ly; concerned"with the preparation of olymeriematerials in which a rubbery copolyrner of a butadiene-'1,'3 hydro?-carbon= and" another l'polymerizable Yconipoun'd such as styrene isuniformly -afidintiniately combined with a-hard' resinous saturatedpolymer of 'achloroethylene containing from one to two chlorin'a'tonisbn'one only of the carbon atoms, that is," vinyl "or vinylidenechloride; 6

Rubbery jcopolymers .of a} buta,diene-,1,'3 hydrocarbon with styrene orits equiv alents onstitute a well k class of materials; 7 Such dienestyrene synthetic cally byfpossessing' long fca'rbbn chain's plicityfoffintra-chai'n carb A e ts high degree of .aliphaticfun s'aturatiori 1(iodine n In generally above about 5,0 r, and are c'haracteri zediphysically by a resernblanceto natural rubber in that'tlie'y ,are

capable of being 'converted'from'an essentially 'plastig'rll workableconditionto alhiglilyelasticconditionby vul- 1 canization, as by heatingWlthlSIllfLlI s Although such butadjen'e styrene syntheticrubb seinblenatural 'rubber' erally much weaker and much less elastic' when,vul'canized in a pureg guirfl'recipe(that a; recipe which includes therubbery material and vulcan i'zing ingredients but is free fromsignificant amounts of other compounding" ingredients such aspigiiientsffillers', softeners; are.

than is natural rubber For example,"pure gum? vulcanizates of naturalrubber possess a tensile strength ranging from 2,000 to 3,000 lbs./sq.in. or more and are highly elastic, whereas pure, gum vulcanizatesofsuch syhthetic rubbers possess tensile strengths 1 generallyless than1,000 lbs/sq; in.',,and often aselow-as .200- to 500 IbsJ/sqt 5 in.,-and are not nearly-so elasticr -As :a result, "such-1* synthetic rubbersmust :be cornpounded with carbon blaclr (which remarkably reinforces thesynthetic rubber;to ,an" extent even greater thanfiit :does with natural:rubberl) -,t o attain sufiicient strength tovbeuseful,:evenrthoughuthisv is undesirable in many 7 instances 'because ofai thezbla'ck' coloration and the increased stiffness of the composition.-

polymers, are the hard;:'solid, resinous, saturated polymers of vinylchloride or. vinylidene chloride. aaThes'e materials: are also :highmolecular weight polymers -(molecularweight generally abov z t5 0,000containing longt carbon chains; but they: differ from the firubberycopolyrners in.

that these chains'are substantiallysaturated the double: bonds of theymonornerjdisappearing ion polymerization),

and a's a result "the 'poly'rner 'pqssessesi anviodine'l number of -zeroor thereabouts; In physical properties1 theseuna l terials also differfrom rubbery 'materials since they are an r s nd eve superior thereto incertain respects',ftlie'y"alsopossess an" outstanding disadvantageascorhpared to natural rubber This disadvantage resides in the fact"that'they are genhfardand stitt at ordinary ten 'pelratures (having 'aBrinell v hardness number in the iinplasticiz ed-condition'withintherangeof abbut l0 to I 50; a's'nieasured" on the Brinell= ap paratu'susingja -2.5 -mm;{ball"WithKa-ZS kg aloadj; f 5 are" not appreciably(elastic unless mixed with plasticizers; I and they -far'ef not'villeanizable' =in thefimannedoffiiatural 1' rubber: lvloreover, theyarejther'moplas'tic;wh'ereas*the" rubbery copolymers stiffen at elevatedternperatures ij 7 described classes with 'certain oft p I or vinylidenechloride-resins ofith second oft fthe' above describediclasses by mixingthe; i

an internalirniiten 'but this practi success Thus'inrnany instances Irnate'rialsiare n compatible with orsoluble in one 'ancgthe'r, and'asxa" to rain for the' rubber copolymerjs of the fi st chloride-"resinous poly'rner s' in'a'y 1ntin1ately: combined' withone another. IV .7

.-A second principal "object is toprovide,ainew classa of synthetic--polymeric materials; which; arerubbery and vulcanizabledn nature,::andhichEreseinbIe natural 'rub befr,- ;-rather"-than butadiene-"-styrenesynthetic ru'bber; n; a

I that; they r'naybe-vulcanized'inia-3*pureygu1n?; recipeatd;

pro'ducefi strong snappy:wvulcanizateswihaving a I tensile! 5 strengthabove-v 1,-000 ;lbs:/sq; in.;=yet' arexfar-superior toi t ral 'z b :r'nf. iresistaricewto; oxidation 0 chemicals e and to :1 oth rdeteriorating"influencesfi'r t and a copolyrrie'riz'able rompouhd suchas styr'en' 4t) aqueousgemulsifying medium -;c ontainin'g dispe'rsarticles: o fija hard saturated resinous p'olynie'r-"of v' a or;nylidene chloride, and then fp'olymerizingg "th said monomeric materialwhile "so zemulsifie'da}: niosti cons .venient 'way gofproceeding -is topolymerize; the mixture of butadienezlgi;hydrocarbon: and'copolyrnerizable com l pqund-in jaqueous; emulsion'zin ;the usual;manner except that-the polymerization is;carried out: in "thepresence-of aypreyiously prepared aqueousdispersion .or latex of the?saturated-yinyl orivinylidentaghldride resin, when prac o tic ingthis-rnethod tsometinies referred to-her'einafter :afor

sak o brevity as see'ding- ,theiemulsionicopolymeriza i ti on forfrninga butadiene-styrenelcopolymer with hard: a saturated vinyl or:vinylidene; chloride resinous polymer),-

,it,lrasbeen found -that-formation of rubbery copol'ymer;-

5 occurs onthe surfaces ofthe particles ofzsaturated resinous 1*aqueous'vdispersion' in which the t l p'o ymer' q p o u e {rubberycopolyrner and; the saturated resin} are present:

013. 1 4 t t t theyare soluble in one anotherfig a 1 When the'hardsaturated resin is present in propo non less than that ofther'rubberycopolymer; the second of irnately' combined, #rega'rdless' f'theabove-st'ated:objects isattained; For inthis instance 'itwhasbeen-foundthat the aqueous dispersion-obtained thei-polyinerization :consists rofparticles containing ;a-"c'ore'f Patented Ju 21 aterials" on a' mill orin a Sa ome blend obtainedi's' ,weaker an 1 less desirablejthan INumerous other" objects "will be ':apparentphereinafterfi l t The firstof the -principal'- objects is attained by thet f rnethodoflthisinvention;,rwhich niethod cornprises theg,

stepsof emulsifying afrnonome'ric inixtu're; polymerizable in aqueous.emulsion '-to';1f0i'itt.{an unsaturated"rubberyn, copolymer, andcomprisingafbutadienek l,-3' 'hydroc'arbon'zma 1: solid;

in thesameiindividual-p ticles. 5. Asa result,"-coag'ulatioii- I 1 v ofthe dispersionproduces a polymeriematerial'ih whichi'.

H the rubber -copolyrner and .,the :{saturated :resinffare uni-Another'class of polymeric materials, tquitezdifferentz-in properties'from the rubbery butadiene-LS estyrene; 'co-' 3 timately dispersed orembedded in a continuous phase the rubbery copolymer. closely resemblenatural rubber in that they are strong and elastic, yet soft andflexible, when vulcanized in a pure gum recipe. They are quite useful inthe production of many articles customarily made from pure gum rubber.

compounds such as nursing nipples, rubber thread, stationers bands,surgical goods, etc., which are superior to those made from butadienestyrene synthetic rubber be-.

cause of a much greater strength and elasticity and are superior tothose made from natural rubber because of a greater resistance tovarious deteriorating influences.

EXAMPLES 1 TO 4 Seeding emulsion copolymerization of butadiene-1,3 andstyrene with latex of polyvinyl chloride In these examples a mixture ofbutadiene-1,3 and styrene (which is polymerizable to form a rubberycopolymer) is emulsified in an aqueous emulsifying medium containingvarying amounts of dispersed, finely-divided particles of polyvinylchloride (which is a hard, saturated resinous polymer insoluble in therubbery butadiene-1,3 styrene copolymer) and is then polymerized whileso emulsified. The precise procedure utilized is as follows:

A polyvinyl chloride latex containing about 19.5% by weight of dispersedpolyvinyl chloride in the form of particles of an average diameter ofabout 0.03 micron is prepared by polymerizing 100 parts of vinylchloride in an aqueous emulsion containing 150 parts of water, 4 partsof fatty acid soap as emulsifying agent, 0.45 part of potassiumpersulfate as polymerization catalyst, and 0.3

part of 28% ammonium hydroxide as a buffer, at a tern-- perature of 50C. for about hrs. (about 95% of the vinyl chloride then being convertedto polymer), and

then diluting the resulting latex to a total solids concentration ofabout. 20%. Varying amounts of this polyvinyl chloride latex .are thenmixed with 90 parts of monomeric butadiene-l,3, 30 parts of monomericstyrene,

2.4 parts of fatty-acid soap, 0.36 part of potassium persulfate, 0.54part of n-dodccyl mercaptan: as a polymerization modifier, andsuflicient water to make a total of about 300 parts, to forma -emulsionsof the monomeric material, which is then polymerized by agitating theemulsions at C. for about 20 hours, after which time about I 80% of themonomers are polymerized. The products consist of aqueous dispersionscontaining finely-divided particles of polymeric material, which onexaminationwith the electron microscope are found to consist of a coreof polyvinyl chloride surrounded by a covering of rubbery butadiene-l,3styrene copolymer. The dispersions are then coagulated by addition ofacid and the polymeric materials washed and dried. I

The polymeric materials are then compounded in a pure gum recipe with 10parts of litharge, 5 parts of zinc oxide, 5 parts of coal tar and 2parts of sulfur foreach 100.parts of butadiene styrene copolymer presenta'ndare then vulcanized by-heating at 307 F. for 45 minutes.

The following table shows the parts of polyvinyl chloride present foreach 100 parts ofrnbbery butadiene-.1,3 styrene copolymer in thepolymeric materials-and the tensile strength, ultimate elongationandmodulus of elasticity at 3.00% elongation of'the vulcanizates. Data on.a butadiene-1,3 styrene copolymer prepared in the same.

Such copolymeric materials way except that no polyvinyl chloride latexwas used is alsoincluded for comparison.

It is apparent that the polymeric materials containing polyvinylchloride are far superior to the control in tensile strength andelasticity and that these improvements are securedwithoutappreciable'stifiening of the vulcanizate. These pure gumvulcanizates are thus more like natural rubber pure gum vulcanizates inphysical properties. These improvements are not se cured however whenit' is attempted to mix polyvinyl chloride and the butadiene-1,3 styrenecopolymer on.

amixing mill or by other conventional methods.

EXAMPLES 5 AND 6 Seeding emulsion copolymerization of butadiene-1,3 andstyrene with latex of polyvinylidene chloride The procedure of thepreceding examples is repeated except that various proportions of apolyvinylidene chloride latex containing about 15% by weight ofpolyvinylidene chloride in the form of small particles of about 0.04micron in average diameter, and prepared by the polymerization 'at 50 C.of parts of vinylidene chloride in an aqueous emulsion containing 367parts of a 2% aqueous soap solution and 0.45 part of potassiumpersulfate, are used in place of the polyvinyl chloride latex. Theamount of polyvinylidene chloride present for each parts of thebutadiene styrene co polymer formed by the polymerization, and thephysical properties of the polymeric materials obtained when vulcanizedin the pure gum recipe set forth in the preceding examples, are asfollows:

in-a V y1 ene Chloride Tensile Ultimate g per 100 parts Strength,Elongation lbs Butadtene-L3 lbs./sq.h1. (percent) h Styrene Copolymer25o 300 I 250 .6 1,100 840 275 Examplefin. 51.4 1,200 640 350.

increases the tensile strength and elasticity of the pure gumvulcanizate without greatly affecting the modulus.

J As in the case of polyvinyl chloride, this improvement is not securedwhen it is attempted to mill mix the polyvinylidene chloride and therubbery copolymer, which are not compatible with one another.

Substantially equivalent results are secured when using in place ofpolyvinyl chloride or .polyvinylidene chloride, other hard saturatedresins preparedby the polymerization of a monomeric mixture consistingpredominantlyv of vinyl chloride or vinylidene chloride such as thecopolymers of vinyl chloride and vinylidene chl0-.

ride and the copolymers of either of these with other monomerscontaining a single olefinic double bond such as. ethyl acrylate, butylacrylate, methyl methacrylate.

acrylonitrile, diethyl-maleate .and the. like.

In the examples the monomeric mixture ofbutadiene 1,3 hydrocarbon andcopolymerizable compound which is polymerized. to form arubbery.copolymer, has been a mixture of butadiene- 1,3[and styrene] .vsaausiomqmixtures are substantially equivalent respect-t the specific mixturesused and-maybe siilzastituted therefor. For example, therejmay beftised;mixtures lcon{ taining a predominant amount, of any. fbutadiene-Lshydrocarbons such as iness-1, rapi t '{Z B dI- methyl butadiene-1,3or'piperylene or 'a "combinationfof two or more of these. and a. lesser,,amountotf one; or more of the following. monomers; ;styrene;alpha-methyl" styrene, p-methoxy1styrenefp chloro styrene, dichloroaromatic compounds ofthe formula styrene, vinyl naphthalene andothertallr'enyl substituted wherein Ar is an aromatic radical having itsconnect ing valence on a ring carbon atom and R is'hydrogen or alkyl.

It is preferred that the saturated'vinyl or vinylidene chloride resin beprepared by polymerization in faqueous emulsion and that the dispersionor'latexobtained be utilized to supply the resin, and it isalsoxpreferreidthat the particles of resin in thelatex beno'i greaterthan;

about 0.4 micron in averagediameter, andFinorepref-Q. erably lessthanabout 0.1 micron in average diameten; but other proceduresforsupplying the resin in dispersed form' are also included. ,It is alsopreferred that the resin possess a Brinell hardness number jwifllinptherange of about 10m when measured on the Brinell apparatus using a2.Sjmm.'ball with a 25 kg. load, as do the resins used in the specificexamples. 9

merization, and in each instance a rubbery. vulcanizable em of a hardsaturated resinous polymer ofa monomeric polymeric material ofconsiderably higher. tensile strengththan the rubbery copolymer aloneisobtained, How-g ever, polymeric materials most useful for most punposesare secured when the proportion of hardlsaturat'ed more preferably fromresin is from about 5 to 80 parts,

about 15 to parts, toeach 1'00 partsfof rubbery co-- polymer, since suchpolymeric materials when yulcan- 7 'ized give strong snappy-pure gumvulcanizatesf re.-

sembling those obtainablefromnatural rubberwj When the proportion ofresin-is increased to'about80 fto 100' parts for each 100-parts ofrubberyycopolymer, the";

polymeric materials are still capable of vulcanization but are somewhatstifler and more lilre leath'er when" vulcanized.

In addition to the above-discussed modifications and variations in thenaturejand proportions of essential materials used in practicing theinvention, other modifir cations and variations from' the specificexamples are also possible. Thus, in polymerizing the monomer mixf turecontaining butadiene.-1,3 hydrocarbonand' styrcne in aqueous emulsion inthe presence of .adispersron 1; anfu ra rubbrycbpolymerandbontaihingj,

of the resin, use maybemade 'of any of the various emulsifying agents,polymerization catalystsgpolymen ization modifiers, etc. commonlyemployed 'inthepolymerization of butadiene-1,3 hydrocarbon. containingmixtures in aqueous emulsion. The conditions ofpolyvmerization such astime and temperature" and-degree of agitation may also be .varied inaccordance with: established procedures. Similar variations may be madein the polymerization to form'theihard saturated resin polymerization inaqueous h V v C t r m emulsion in the presence of a previously preparedaque- The products of the polymerizationskdescribed are Y first obtainedin the form of an aqueous dispersion or 1 latex. These latices maybeused a's'such or they may if it is formed by previous emulsion.

the art, to yield the polymeric product in solid form.

theappendedclaim t Thisapplication is. afdlvisionbf copendingapplication I present at the i c pq ym r f r e yv t t coagulatingthe"aqueous dispersiontherebyobtalne in ;polymerizingIa;monomermixturepolymerizable t'of form, an'-- unsaturated jirubbe'ry copolymer andcontaining .lc xfij jis ns-p s 'a l aiv 9- m n n v r' sidam Jeterpfhard, 'saturat'ed polyvinyl,chloridei I rial present; at theibe'ginningfof the "polymerr; v p p saturated resinousjpolymer-alsogheing tromi aboutf-{li to =1 60 by Weight of the rubberycopolymer formed ,by ithe j a polymerization, andthenfcoagulatingthe'fai ueous disg polymericImaterialsconsisting V V I 1fiforc'edis flely by organicresinousmaterial,-g;vvhich consists.

which particles of hard saturated". resin; pa poundin i" ingredients.such as.

p softeners, plasticizersppigments,fillers; colors, stabilizing, agents,antioxidants, jvulcanizing ingredients, etc. I maybe-added thedispersiontbefore coagulation or to the soli roducts aftertcoagulationin the,

' ofthe art,jif de'sired, it'being3un-j ence orahsencegof suchlmaterialsset forth, i

, A, s N V I s ulcaniaable, polymeric materials cons1stingojrubberymaterial 'rin forced solely byorganic:resinousmaterial, whichconsists;ini polymerizing, a monomer-f mixture polymerizable @to form; anunsaturated-rubbery copolyrnerand' containing fromiaboutr50Y-to .90%y}"Weight'of butadiene 1 3fiand the; remainder of styrene; in an aqueousi'emulsion in the presence of:ja previously prepared aqueouszdispersion' comprising particles below .07. 4 micron in aY 3 idiammaterial consisting predominantly of, vinyl :chloride, fth saidsaturated resinous polymer being insoluble in' th said rubbery cop'osinous; Tpolymer also; her 'arnount'from 5 to .00%;by we 119 th v Vly'meriz'atio ;5 ;2.1 an; i emoamr fproducing. 'rubber'y- {yulcanizahlepolymeric materialsfconsisting"of rubheryfimaterial rein- 'forcedsolelyiby organic resinous-rnateria1, which consists froniiabout- 501.to90%- blwight?offbutadiene-13f and 1 ,j the iremainde 'ofstyrene-infanaqueous emulsion'jin'the.

presence f a previously' prepared "aqueous'fdisper"- proportion ofikthelsaid saturated fres'in being the said-rubbery; 'copolymeri-and being"the, sol

'persion' thereby'obtained.

3.1Th 'e method; {offproducing; rubbery vulcanizable I of rubberymaterialfrei in polymerizin'gj a rn'onorner mixture-fpolymerizablci towherein, Ar is .an'aromatic radical having its connecting valenceion aring f ca'rbonfatom {and R is selected from ,the class consistingof-hydrogenand alkyLin an aqueous ous dispersion comprising particlesvbelow-0.4 micron in average. diameter ofhard,saturatediresinous polymerof a chloroethylenecontaining fror nj'l to' -zchlorine atoms, becoagulated by any of the methods vell known-t0.

At this stage, the polymeric products of this invention] comprise acontinuous phase of ruhbery copolymerin onone {only ofQthe carbonato'nis, the said saturated, ,7 ifr esinous polymer being insolubleinfthe said rubbery t "copol ymer and being thesole solidmaterial presentat the heginningof the .polymerization' saidsaturatd resinous polymeralso being present in an amount from 5 to 100% by weight of that of therubbery copolyrner formed by the polymerization, and then coagulatingthe aqueous dispersion thereby obtained.

4. The method of producing rubbery vnlcanizable polymeric materialsconsisting of rubbery material reinforced solely by organic resinousmaterial, which consists in polymerizing a monomer mixture polymerizableto form an unsaturated rubbery copolymer and containing from about 50 to90% by weight of butadiene-1,3 and the remainder of styrene in anaqueous emulsion in the presence of a previously prepared aqueousdispersion comprising particles below 0.4 micron'in average diam-References Cited in the file of this pa tent TUNrrEpsTATEs PATENTS2,512,697 .-Grotenhuis June 27, 1950

3. THE METHOD OF PRODUCING RUBBERY VULCANIZABLE POLYMERIC MATERIALSCONSISTING OF RUBBERY MATERIAL REINFORCED SOLEY BY ORGANIC RESINOUSMATERIAL, WHICH CONSISTS IN POLYMERIZING A MONOMER MIXTURE POLYMERIZABLETO FORM AN UNSATURATED RUBBERY COPOLYMER AND CONTAINING FROM ABOUT 50 TO90% BY WEIGHT OF A BUTADIENE-1,3 HYDROCARBON AND THE REMAINDER OF ANALKENYL SUBSTITUTED AROMATIC COMPOUND OF THE FORMULA